﻿using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading;
using Legend.Threading;

namespace Legend.Collections
{
    /// <summary>
    /// Wrapps another collection to synchronize the access of it.
    /// </summary>
    /// <typeparam name="T">The type of items in the collection.</typeparam>
    public class SynchronizedCollection<T>
        : ICollection<T>, ISynchronizable
    {
        protected readonly ICollection<T> collection;
        protected readonly ISynchronizationManager synchronizationManager;

        /// <summary>
        /// Initializes a new instance of the <see cref="SynchronizedCollection&lt;T&gt;"/> class.
        /// </summary>
        /// <param name="collection">The collection.</param>
        /// <param name="synchronizationManager">The reader writer lock to use for synchronization.</param>
        /// <exception cref="ArgumentNullException">The specified collection is null -or-
        /// the specified readerWriterLock is null.</exception>
        /// <exception cref="ArgumentException">The specified readerWriterLock does not support
        /// recursion.</exception>
        public SynchronizedCollection(ICollection<T> collection, ISynchronizationManager synchronizationManager)
        {
            Require.ThatArgument(collection).Named("collection").IsNotNull();
            Require.ThatArgument(synchronizationManager).Named("synchronizationManager").IsNotNull();

            if (synchronizationManager.RecursionPolicy != LockRecursionPolicy.SupportsRecursion)
            {
                throw new ArgumentException("The specified ISynchronizationManager does not support recursion.");
            }

            this.collection = collection;
            this.synchronizationManager = synchronizationManager;
        }

        /// <summary>
        /// Adds an item to the <see cref="T:System.Collections.Generic.ICollection`1"/>.
        /// </summary>
        /// <param name="item">The object to add to the <see cref="T:System.Collections.Generic.ICollection`1"/>.</param>
        /// <exception cref="T:System.NotSupportedException">
        /// The <see cref="T:System.Collections.Generic.ICollection`1"/> is read-only.
        /// </exception>
        public void Add(T item)
        {
            using (this.AcquireWriteLock())
            {
                collection.Add(item);
            }
        }

        /// <summary>
        /// Removes all items from the <see cref="T:System.Collections.Generic.ICollection`1"/>.
        /// </summary>
        /// <exception cref="T:System.NotSupportedException">
        /// The <see cref="T:System.Collections.Generic.ICollection`1"/> is read-only.
        /// </exception>
        public void Clear()
        {
            using (this.AcquireWriteLock())
            {
                collection.Clear();
            }            
        }

        /// <summary>
        /// Determines whether the <see cref="T:System.Collections.Generic.ICollection`1"/> contains a specific value.
        /// </summary>
        /// <param name="item">The object to locate in the <see cref="T:System.Collections.Generic.ICollection`1"/>.</param>
        /// <returns>
        /// true if <paramref name="item"/> is found in the <see cref="T:System.Collections.Generic.ICollection`1"/>; otherwise, false.
        /// </returns>
        public bool Contains(T item)
        {
            using (this.AcquireReadLock())
            {
                return collection.Contains(item);
            }
        }

        /// <summary>
        /// Copies the elements of the <see cref="T:System.Collections.Generic.ICollection`1"/> to an <see cref="T:System.Array"/>, starting at a particular <see cref="T:System.Array"/> index.
        /// </summary>
        /// <param name="array">The one-dimensional <see cref="T:System.Array"/> that is the destination of the elements copied from <see cref="T:System.Collections.Generic.ICollection`1"/>. The <see cref="T:System.Array"/> must have zero-based indexing.</param>
        /// <param name="arrayIndex">The zero-based index in <paramref name="array"/> at which copying begins.</param>
        /// <exception cref="T:System.ArgumentNullException">
        /// 	<paramref name="array"/> is null.
        /// </exception>
        /// <exception cref="T:System.ArgumentOutOfRangeException">
        /// 	<paramref name="arrayIndex"/> is less than 0.
        /// </exception>
        /// <exception cref="T:System.ArgumentException">
        /// 	<paramref name="array"/> is multidimensional.
        /// -or-
        /// <paramref name="arrayIndex"/> is equal to or greater than the length of <paramref name="array"/>.
        /// -or-
        /// The number of elements in the source <see cref="T:System.Collections.Generic.ICollection`1"/> is greater than the available space from <paramref name="arrayIndex"/> to the end of the destination <paramref name="array"/>.
        /// -or-
        /// Type <typeparamref name="T"/> cannot be cast automatically to the type of the destination <paramref name="array"/>.
        /// </exception>
        public void CopyTo(T[] array, int arrayIndex)
        {
            using (this.AcquireReadLock())
            {
                collection.CopyTo(array, arrayIndex);
            }
        }

        /// <summary>
        /// Gets the number of elements contained in the <see cref="T:System.Collections.Generic.ICollection`1"/>.
        /// </summary>
        /// <value></value>
        /// <returns>
        /// The number of elements contained in the <see cref="T:System.Collections.Generic.ICollection`1"/>.
        /// </returns>
        public int Count
        {
            get 
            {
                using (this.AcquireReadLock())
                {
                    return collection.Count;
                }
            }
        }

        /// <summary>
        /// Gets the ISynchronizationManager that's used to
        /// manage the synchronization of the collection.
        /// </summary>
        public ISynchronizationManager SynchronizationManager
        {
            get 
            { 
                return synchronizationManager; 
            }
        }

        /// <summary>
        /// Gets a value indicating whether the <see cref="T:System.Collections.Generic.ICollection`1"/> is read-only.
        /// </summary>
        /// <value></value>
        /// <returns>true if the <see cref="T:System.Collections.Generic.ICollection`1"/> is read-only; otherwise, false.
        /// </returns>
        public bool IsReadOnly
        {
            get 
            {
                return collection.IsReadOnly;
            }
        }

        /// <summary>
        /// Removes the first occurrence of a specific object from the <see cref="T:System.Collections.Generic.ICollection`1"/>.
        /// </summary>
        /// <param name="item">The object to remove from the <see cref="T:System.Collections.Generic.ICollection`1"/>.</param>
        /// <returns>
        /// true if <paramref name="item"/> was successfully removed from the <see cref="T:System.Collections.Generic.ICollection`1"/>; otherwise, false. This method also returns false if <paramref name="item"/> is not found in the original <see cref="T:System.Collections.Generic.ICollection`1"/>.
        /// </returns>
        /// <exception cref="T:System.NotSupportedException">
        /// The <see cref="T:System.Collections.Generic.ICollection`1"/> is read-only.
        /// </exception>
        public bool Remove(T item)
        {
            using (this.AcquireWriteLock())
            {
                return collection.Remove(item);
            }
        }

        /// <summary>
        /// Returns an enumerator that iterates through the collection.
        /// </summary>
        /// <returns>
        /// A <see cref="T:System.Collections.Generic.IEnumerator`1"/> that can be used to iterate through the collection.
        /// </returns>
        public IEnumerator<T> GetEnumerator()
        {
            return new LockingEnumerator<T>(collection.GetEnumerator(), synchronizationManager);
        }

        System.Collections.IEnumerator System.Collections.IEnumerable.GetEnumerator()
        {
            return this.GetEnumerator();
        }
    }
}